This application relates to electronic signaling and, more particularly, to visually displaying status information in an electronic signaling system, such as those found in network repeaters and switches.
Many computer networks rely on repeaters to facilitate the exchange of information among the computers in the network. In many networks, such as Ethernet networks, information is exchanged in the form of data packets that pass through each of the repeaters in the network. The repeaters usually monitor the data packets to collect information on the status of network resources. Network administrators then use the status information to manage the network resources.
One way of conveying the status information from a repeater to a network administrator is through visual indicators, such as an array of light emitting diodes (LEDs). In general, each LED in the array is dedicated to presenting information about a particular status condition on a particular repeater port. The network administrator can determine whether a particular status condition exists on a status port by observing whether the corresponding LED in the array is illuminated. One problem with this technique is that additional pins must be added to the repeater chip to deliver status signals to the LED array, thus driving up the cost and complexity of the repeater chip.
Sophisticated techniques have been developed to reduce the number of signal lines required to drive an LED indicator array in a network repeater. One such technique is described in U.S. Pat. No. 5,598,418, in which a 16xc3x975 array of LEDs provides information about five status conditions for each of sixteen repeater ports. The LED array is driven by eight time-multiplexed signals, each of which carries information about all five status conditions for two of the sixteen repeater ports. While this technique for driving the LED array succeeds in placing a great deal of information on very few status lines, the technique requires a relatively sophisticated multiplexing circuit in the repeater chip and an equally sophisticated demultiplexing scheme at the LED array. For example, this technique requires dual buffer circuits that operate alternately to decode the multiplexed status signals. Moreover, this technique still requires one pin for each repeater port and one pin for each status condition for which information is provided. For a 16xc3x975 array, the repeater chip must include twenty-one additional pins.
The invention provides a simple solution for driving an indicator array with relatively few signal lines from a repeater chip. The indicators are arranged so that a single status line can drive a pair of rows (or columns). As a result, the number of pins dedicated to driving the rows (or columns) of the indicator array is no more than one-half of the number of rows (or columns) in the array. For example, a repeater implementing the invention can drive a 16xc3x975 array with only thirteen dedicated pins (8xc3x975). Moreover, the invention allows the use of standard selector circuits and a relatively simple row selection circuit in driving the indicator array.
In one aspect, the invention involves visually presenting status information from an electronic signaling system, such as those often found in network repeaters and switches. At least one pair of visual indicator devices (e.g., LEDs arranged to conduct in opposite directions) provides the visual information. An enable line is connected to both LEDs in the pair to deliver an enable signal directly to the LEDs. A status line also is connected to both LEDs in the pair. A selector circuit receives at least two status signals containing status information and then selectively applies the status signals to the status line.
In some embodiments, one of the LEDs in each pair conducts only when the enable signal has a high value, and the other LED conducts only when the enable signal has a low value. For example, the LEDs operate in this manner when the cathode of each LED in a pair is connected to the anode of the other LED in the pair. In other embodiments, the selector circuit selects the status signals one at a time.
Some embodiments include at least one additional pair of indicator devices connected to the enable line and another status line connected to both indicator devices in the additional pair. Some of these embodiments include an additional selector circuit that receives at least two additional status signals containing status information and then selectively applies the additional status signals to the additional status line.
Other embodiments include at least one additional pair of indicator devices connected to the status line and another enable line connected to both indicator devices in the additional pair. The additional enable line delivers another enable signal directly to the additional indicator devices.
Still other embodiments include an enable circuit that generates the enable signal such that each of the indicator devices in the pair is enabled when the selector circuit applies a corresponding one of the status signals to the status line. Some embodiments include a logic circuit having inputs coupled to the enable line and the selector circuit and having an output that drives the status line. The logic circuit often consists of an XOR gate.
In another aspect, the invention features an electronic signaling system that includes at least two status condition lines to carry status information. A visual indicator array having at least one pair of indicator devices, such as LEDs, displays the status information visually. An enable line is connected to both of the LEDs in the pair to deliver an enable signal directly to the LEDs. A status line also connects to both LEDs in the pair. A selector circuit is coupled to the status condition lines to selectively apply the status information to the status line.
In some embodiments, the signaling system includes at least two ports for which status information is generated, and each of the LEDs in a pair is dedicated to displaying status information for a corresponding one of the ports. In some cases, the LEDs are arranged SO that one of the LEDs provides a visual output only when the enable signal has a high value and a status signal associated with the corresponding port has a high value. In these cases, the other LED provides a visual output only when the enable signal has a low value and a status signal associated with the corresponding port has a high value.
In another aspect, the invention features a visual indicator array having (Mxc3x97N)/2 pairs of indicator devices arranged in a two-dimensional, linear array having M rows and N columns, where M is an integer greater than or equal to two, and N is an integer greater than or equal to one. The array also includes M/2 enable lines, each of which is connected to all of the indicator devices in two of the M rows to deliver enable signals to the indicator devices in the two rows. Likewise, each of N status lines is connected to all of the indicator devices in one of the N columns. Status information is carried by Mxc3x97N status signals, and each of N selectors is connected to a corresponding one of the status lines. Each of the N selectors receives M of the status signals and selectively applies the M status signals to the corresponding status line one at a time.